JP2001340950A - Method for measuring slab length in continuous casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring a slab length in the continuous casting machine which performs an abnormality detection through a measuring roll in high accuracy and prevents an unnecessary changeover to a backup measuring in a final driving roll. SOLUTION: A speed operation value through a measuring roll 28 is compared with a speed feedback value through a speed master pinch roll 14M for controlling a casting speed and when the difference between the two values grows bigger, a changeover from the measurement through the measuring roll 28 to a backup measuring through the final driving roll 14F is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a slab length of a continuous casting machine, and more particularly to a continuous slab measuring method in which a measuring roll is switched from a measuring roll to a final driving roll when a measuring roll fails. The present invention relates to an improvement of a slab length measuring method of a casting machine.

[0002]

2. Description of the Related Art Generally, in a continuous casting machine, as shown in FIG.
A large number of pinch rolls 14 driven by a motor (M) 18 are pulled out while changing the direction from a vertical direction to a horizontal direction, conveyed by conveying rolls 24, cut by a slab cutting machine 26, and cut by a predetermined length. It will be a slab.

[0003] The slab 10 in such a continuous casting machine is used.
In general, the measuring roll 28, which is a non-driving roll capable of performing accurate measurement without driving slip, is rotated by the slab 10, and a pulse generator (PLG) connected to the measuring roll 28 For example, the output of 30 is counted by a counter 42 in a speed control programming controller (PLC) 40. However, when an abnormality such as a failure occurs in the measuring roll 28, the pulse generator (PL) connected to the motor 18F driving the final driving pinch roll (hereinafter simply referred to as final driving roll) 14F.
G) The output of 20F is backed up by counting by the counter 44.

Here, the failure of the conventional measuring roll 28 is detected by monitoring a timer (T) when the output pulse of the PLG 30 is lost and the predetermined time (failure determination time T) does not change. The circuit 46 recognizes the failure,
By switching the changeover switch 48, the output of the PLG 20F of the final drive roll 14F is input to the slab length measuring circuit 50,
I have a backup.

In the drawing, a double line “=” indicates a mechanical connection, a thick solid line indicates a power cable, a thin solid line indicates a control system cable, and 16 indicates a pinch roll drive motor 18 provided for each pinch roll 14. A pinch roll drive circuit including a pulse generator 20 connected to the motor 18, an inverter (INV) 22 for controlling the motor 18 according to the difference between the output of the pulse generator 20 and the speed command, 52 Proportion for giving speed commands to all the pinch roll drive circuits 16 according to the difference between the speed feedback (FB) value output from the drive circuit 16M of the pinch roll (hereinafter simply referred to as a speed master roll) 14M and the set speed. It is an integral (PI) controller.

[0006]

However, in the above method, when the failure determination time T is long, the failure detection of the measuring roll is delayed, and during that time, the slab length cannot be measured. Conversely, if the failure determination time T is short, a pulse omission is erroneously detected in a case where the casting speed is low,
Switching to backup by the output of the final drive roll more than necessary results in a decrease in length measurement accuracy. In general, the length measurement by the driving roll is less accurate than the length measurement by the non-drive roll due to the occurrence of the slip.

Japanese Patent Application Laid-Open No. 4-339554 discloses that when the pinch roll is not the speed reference pinch roll, the difference between the pulse generator of the speed reference pinch roll and the current speed calculated from the pulse of the pulse generator of the pinch roll is calculated. When the pinch roll is a speed reference pinch roll, a difference between the actual speed average value of each pinch roll and the calculated error is compared with the allowable error to detect an abnormality. However, it did not detect abnormality of the measuring roll.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. By performing high-precision detection of an abnormality of a measuring roll, it is possible to switch to a backup length measurement using a final driving roll more than necessary. It is an object to prevent the measurement accuracy from lowering.

[0009]

According to the present invention, when a measuring roll is abnormal, the length of the measuring roll can be measured.
In the method for measuring the slab length of a continuous casting machine in which the length is switched to the length measurement by a final drive roll, a speed calculation value or a length measurement value by a measuring roll and a speed feedback value or a slab by a speed master pinch roll for casting speed control. The above problem is solved by comparing the lengths and, when the difference between the two becomes large, switching from the length measurement by the measuring roll to the length measurement by the final driving roll.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In this embodiment, as shown in FIG. 1, in the slab length measuring system of the continuous casting machine similar to the conventional example shown in FIG. 2, the output pulse of the measuring roll 28 is used instead of the timer monitoring circuit 46. A speed calculating circuit 60 for calculating the speed from the output of the counter 42 for counting, the speed calculated by the speed calculating circuit 60 and the speed master roll 14
And a comparison circuit 62 for comparing the speed feedback (FB) value calculated by the M driving circuit 16M. When the comparison circuit 62 detects that the difference between the two has become larger than a set value, a changeover switch is provided. 48, and the final drive roll 14
The backup measurement is switched to F.

In this manner, the speed control PLC 40 calculates the speed of the measuring roll 28, compares it with the speed feedback value of the existing speed master roll 14M, and finally drives the slab length measurement counter according to the comparison result. By switching to the roll 14F, a failure of the measuring roll can be properly detected according to the casting speed.

In the above-described embodiment, the speed is calculated from the output pulse of the measuring roll and compared with the speed FB value by the speed master roll.
It is also possible to determine the slab length by integrating the speed FB value and compare the slab length with the length measurement value by the measuring roll to detect a failure.

The present invention is not limited to continuous casting of slabs, but can also be applied to continuous casting of blooms.

[0015]

According to the present invention, it is possible to detect the abnormality of the measuring roll with high accuracy, to reduce the opportunity for backup length measurement by the final drive roll, and to perform high-precision length measurement.

According to the test results of the inventors, the backup length measurement by the final drive roll could be reduced by half.
In addition, detection of a failure is not lost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view, including a partial block diagram, showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view, including a partial block diagram, showing an example of a conventional slab length measuring system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Slab 12 ... Mold 14 ... Pinch roll 14F ... Final drive (pinch) roll 14M ... Speed master (pinch) roll 16 ... Pinch roll drive circuit 20, 30 ... Pulse generator (PLG) 28 ... Measuring roll (MR) 40 ... Speed control programming controller (PLC) 42, 44 ... Counter 48 ... Changeover switch 50 ... Slab length measurement circuit 60 ... Speed calculation circuit 62 ... Comparison circuit

Claims (1)

[Claims] In a slab length measuring method for a continuous casting machine, in which a measuring roll is switched from a length measuring by a measuring roll to a length measuring by a final driving roll when a measuring roll is abnormal, a speed calculation value or a length measuring by a measuring roll is provided. The value is compared with the speed feedback value or the slab length by the speed master pinch roll for pouring speed control, and when the difference between the two becomes large, the measurement is switched from the length measurement by the measuring roll to the length measurement by the final drive roll. A slab length measuring method for a continuous casting machine, characterized in that: